<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    .box{
      width: 200px;
      height: 200px;
      background-color: skyblue;
      display:flex;
      flex-direction: column;
      justify-content: space-around
    }
    /*弹性布局的item属性是写在item的style里面*/
    /*order属性,数值越小,排列越靠前*/
  </style>
</head>
<body>
  <div class="box">
    <div style="order:2">item1</div>
    <div style="order:3">item2</div>
    <div style="order:1">item3</div>
  </div>
</body>
</html>